from math import sqrt,pow
x1,y1,x2,y2=map(float,input().split())
print("{0}".format(sqrt(pow(x2-x1,2)+pow(y2-y1,2)))) from math import sqrt,pow x1,y1,x2,y2=map(float,input().split()) x1 map(float,input().split()) map float input().split() ().split () input split y1 x2 y2 print("{0}".format(sqrt(pow(x2-x1,2)+pow(y2-y1,2)))) print "{0}".format(sqrt(pow(x2-x1,2)+pow(y2-y1,2))) "{0}".format "{0}" format sqrt(pow(x2-x1,2)+pow(y2-y1,2)) sqrt pow(x2-x1,2)+pow(y2-y1,2) pow(x2-x1,2) pow x2-x1 x2 x1 2 pow(y2-y1,2) pow y2-y1 y2 y1 2 x1,y1,x2,y2=map(float,input().split()) map(float,input().split()) x1 y2=map(float,input().split()) map(float,input().split()) y2 y1,x2,y2=map(float,input().split()) map(float,input().split()) y1 x2,y2=map(float,input().split()) map(float,input().split()) x2
from math import sqrt,pow
x1,y1,x2,y2=map(float,input().split())
print("{0}".format(sqrt(pow(x2-x1,2)+pow(y2-y1,2))))